Use of alginates to treat bauxite red mud

Abstract

Alginic acid is used in combination with high molecular weight synthetic water soluble polymers to flocculate red mud from Bayer process liquors. Superior clarity of supernatant liquor is achieved using the process of the invention.

Having thus described our invention, we claim: 
     
       1. A process for separating Bayer process red mud from a Bayer process liquor which comprises the steps of: adding to a Bayer process liquor containing red mud an effective amount of a high molecular weight anionic water soluble flocculant having a molecular weight of at least 10,000,000 and selected from the group consisting of alkali metal and ammonium polyacrylates, and a suspended solids reducing concentration amount of a water soluble alginic acid clarification aid having a molecular weight of about 10,000 to about 250,000;   mixing said flocculant and alginic acid clarification aid with the Bayer process liquor;   allowing the red mud contained in the Bayer process liquor to settle; and then,   separating the red mud from the Bayer process liquor.   
     
     
       2. The process of claim 1 wherein the clarification aid is sodium alginate. 
     
     
       3. The process of claim 2 wherein the high molecular weight anionic flocculant and the water soluble clarification aid are added to a primary settler feed. 
     
     
       4. The process of claim 1 wherein from about 0.05 to 100 mg of alginic acid clarification aid is added per liter of Bayer process liquor. 
     
     
       5. The process of claim 1 wherein from about 0.1 to 50 mg of alginic acid clarification aid is added per liter of Bayer process liquor. 
     
     
       6. The process of claim 1 wherein from about 0.15 to 20 mg of alginic acid clarification aid is added per liter of Bayer process liquor.